I've purchased this type of unit in the past and found it to work well. Hence, when I needed another unit for an en suite refurb, I've have again purchased a similar kit. This time, it will be to provide secondary, independent lighting over the shower cubicle, as well as extraction.
The kit comes with most of the necessary components supplied. However, there's no anti backdraught flap / valve (which is the reason for 4 stars). That's a fair enough omission as one is not always required. However, in my case. I'm venting through the roof and need something to prevent a cold draught blowing straight through into my otherwise nice warm facility.
I have yet to fit this kit (builder delays!) so cannot comment on the noise level or fan extraction efficiency of this particular unit but if it works as well as the other one I have fitted elsewhere, it should be fine.
I have got the version that allows the fan to be wired up for overrun and the time setting is adjustable (or can be disabled). For the price paid for this unit, it's a reasonable buy, with the only additional cost being for a suitable "non return valve".
The previous one I bought was fitted in a guest area and has had only periodic usage. Hopefully, this new unit will have a reasonable lifecycle as it will be in everyday use. Time will tell.